I almost finished building my CNC engraving machine using the Acro system and parts from broken 3D printer and too-small CNC engraving machine. I used pegboard as spoil board. I 3D-printed hold-down clamps that plug into the pegboard but they loosen and the job was ruined. The pegboard is attached to 3/4" thick plywood and I'm not sure about screwing the hold-down clamps to the plywood. Any suggestions?